The present invention relates to an air interface apparatus for use in a high-frequency probe device; and, more particularly, to an air interface apparatus, which performs an interfacing function for transmitting high-frequency signals between a test device and the probe device used in testing electronic products and/or PCB boards, and whose inside is filled with air having a high relative dielectric constant to thereby improve signal transmission efficiency thereof.
A printed circuit board (PCB) is an electronic product including a plurality of chips which are mounted on the surface of the PCB and are electrically connected to each other through buses formed on the surface of the PCB. The buses are formed by coating conductive materials along lines drawn on the surface of the PCB. The chips execute various functions and exchange electrical signals with each other through the buses.
A large scale integrated micro-chip is formed by integrating the PCB into high density and has predominant influence on the performance of an electronic product employing it therein. Therefore, in order to test whether the micro-chip included in the electronic product operates properly or not, it is required to test the micro-chip by using a test device. In performing the test, a probe device is used and more than one probe device are employed in a socket device for the test.
FIGS. 1A and 1B provide views of conventional probe devices employing a coil spring and an insulator.
The conventional probe device 100 has a plural type and a single type as shown in FIGS. 1A and 1B, respectively. In both of the plural and the single types, the probe device 100 includes a fixing block unit 120, a probe pin 110 whose one end is projected from an upper penetration hole of the fixing block unit 120, a coil spring 130 which is inserted into the fixing block unit 120 and whose one side encloses the other end of the probe pin 110, and a signal pin 140 whose one end is enclosed by the other side of the coil spring 130 and the other end is projected from a lower penetration hole of the fixing block unit 120.
That is, the probe pin 110 and the signal pin 140 are inserted into both sides of the fixing block unit 120, respectively. The probe pin 110 projected from the upper penetration hole of the fixing block unit 120 contacts an electrode of a micro-chip which is an object under test and the signal pin 140 projected from the lower penetration hole of the fixing block unit 120 contacts an electrode pad 152 of an interface board 150.
In other words, a contacting part of the probe pin 110 contacts the electrode of the object under test and that of the signal pin 140 contacts the electrode pad 152 of the interface board 150.
However, in the conventional probe device 100, since probing tips of the probe pin 110 and the signal pin 140 are in electrical contacts with both the object under test and the electrode pad 152, respectively, by the elastic force of the coil spring 130, the signal transmission path is not long. Therefore, the conventional probe device 100 has been only used to transmit the direct current (DC) or a low-frequency signal of several MHz. For instance, there is no obstacle in transmitting a low-frequency signal having a long wavelength through a transmission path of a limited length. However, in case of transmitting a high-frequency signal of hundreds of MHz or several GHz, since the probe device 110 has to transmit a high-frequency signal having a short wavelength through the transmission path of the limited length, there occurs substantial loss in the signal transmission and, thereafter, the probe device 110 is improper in the transmission of the high-frequency signal.
Furthermore, in the conventional probe device, insulating materials such as Teflon are used to electrically insulate the probe pin 110 and the fixing block unit 120 to thereby control characteristic impedance therebetween. However, the insulating materials have a mechanically unstable structure since it has a weak physical strength and there is caused a propagation delay due to a relative dielectric constant of the insulator such as Teflon.
It is, therefore, an object of the present invention to provide an air interface apparatus for use in a high-frequency probe device, which performs an interfacing function to transmit a high-frequency signal between a test device and the probe device used in testing electronic products or PCBs and whose inside is filled with air having a high relative dielectric constant to thereby increase transmission efficiency.
In accordance with the present invention, there is provided an air interface apparatus used as a signal transmission carrier between an object under test and a probe device when testing the object under test by using the probe device, which comprises: inner conductive means which has a long hollow cylindrical shape and whose both ends are open; outer conductive means whose both ends are open and which surrounds the inner conductive means with a constant gap and has a long cylindrical shape; a first signal pin being contacted to the object under test and inserted into and projected from one end of the inner conductive means; a second signal pin being contacted to the probe device and inserted into and projected from the other end of the inner conductive means; elastic means for supporting the first and the second signal pins within the inner conductive means to make the first and the second signal pins move in and out from both ends of the inner conductive means, respectively, by the elastic force of the elastic means in response to external pressure; and insulating means for insulating the inner conductive means from the outer conductive means, locating between the inner conductive means and the outer conductive means at both ends of the outer conductive means to thereby make the inner and the outer conductive means support each other.